Overview
The present research project shall be partly based on the experience gained with the strengthening of a tunnel by a new reinforced concrete shell on the inside of the existing vault. The new shell is connected with the existing vault via shear reinforcing bars that are post-installed from the inside of the vault. Similar strengthening measures are frequently applied for other reinforced concrete plate and shell structures. However, the shear resistance and the deformation capacity resulting from such measures are largely unknown.
Frequently, reinforced concrete plates and shells need to be strengthened for shear due to changes in the use of structures, due to increased actions on structures, and to account for the hitherto neglected size effect in thick plates and shells. Often, such structural members can be accessed from one side only and post-installed shear reinforcing bars are used.
The present project aims at investigating (both theoretically and experimentally) the shear resistance as well as the deformation capacity of structural members strengthened in this way, providing a reliable basis for their dimensioning and the development of new systems for the repair and strengthening of reinforced concrete structures.
Following methodology was used in this project:
- The 20 or 50 cm thick plates are each a four-point or three-point attempt subjected to fracture.
- A total of 24 large-scale experiments are carried out, evaluated and described in the final report.
- Parallel to the experimental work, the existing theoretical model concepts will be updated and expanded.
- The relevant practice model concepts and instructions for configuring and executing shear reinforcements of reinforced concrete slabs and shells are also summarized in the final report.
Funding
Results
The key result of this project is the theoretical and experimental overview of the shear resistance which leads to the new system for the repair and strenghtening of reinforced concrete structures.
From April 2009 until June 2011 a total of 24 tests to failure on 12 large-scale test specimens were be carried out, interpreted and documented to provide an experimentally verified basis for the dimensioning of corresponding strengthening measures. The final report summarised the experimental findings, describe relevant theoretical models and provide guidelines for the practical design and execution of shear reinforcing measures for reinforced concrete plates and shells.
Innovation aspects
The purpose of this project fundamental knowledge on the use of shear force reinforcements in only accessible from one side plates or trays made of reinforced concrete is being developed. Thus, there is provided a reliable basis for the assessment and for possible system developments in the field of repair and strengthening of reinforced concrete structures.
Policy implications
The research results will be implemented through the teaching, scientific publications and reports in professional bodies and on the monitoring of selected projects in practice.